1. Field of Invention
This patent application describes the culturing and implantation of cultured human cells onto synthetic or biosynthetic scaffolds to provide a enervated tissue replacement for use in replacing certain skin and soft tissue features such as finger tips, ears, or more preferably breast to reconstruct the areola or nipple.
2. Description of Prior Art
1 in 8 women in the United States will be diagnosed with cancer of the breast. Therapy for breast cancer remains primarily surgical involving breast mastectomy, quadrantectomy, or other types of resections. Breast cancer surgery can be highly disfiguring despite best efforts on the part of the reconstructive surgeon. The nipple and the areolar regions of the breast are frequently removed during breast resection, and reconstruction of this area has been very difficult. Currently, reconstruction efforts are not able to effectively reproduce neither the appearance, nor the sensation of the nipple and areola.
Tissue culture techniques are being successfully used in developing tissue and organ equivalents. The basis for these techniques involve collagen matrix structures or scaffolds, which are capable of being remodeled into functional tissue and organs by employing the right combination of living cells, nutrients, and culturing conditions. Tissue equivalents have been described extensively in many patents, including U.S. Pat. Nos. 4,485,096; 4,485,097; 4,539,716; 4,546,500; 4,604,346; 4,837,379; and 5,827,641, all of which are incorporated herein by reference. One successful application of the tissue equivalent is the living skin equivalent, which has morphology similar to actual human skin. The living skin equivalent is composed of two layers: the upper portion is made of differentiated and stratified human epidermal keratinocytes that cover a thicker, lower layer of human dermal fibroblasts in a collagen matrix. Bell, et al., “Recipes for Reconstituting Skin,” J. of Biochemical Engineering, 113:113-119 (1991).
Cell transplantation has been proposed as an alternative for total organ replacement for a variety of therapeutic needs, including treatment of diseases in the eye, brain, liver, skin, cartilage, and blood vessels. See, for example, J P Vacanti et al., J. Pediat. Surg., Vol. 23, 1988, pp. 3-9; P Aebischer et al., Brain Res. Vol. 488, 1998, pp. 364-368; C B Weinberg and E. Bell, Science, Vol. 231, 1986 pp. 397-400; I V Yannas, Collagen III, M E Nimni, ed., CRC Press, Boca Raton, 1988; G L Bumgardner et al., Hepatology, Vol. 8, 1988, pp. 1158-1161; A M Sun et al., Appl. Bioch. Biotech., Vol. 10, 1984, pp. 87-99; A A Demetriou et al., Proc. Nat. Acad. Sci. USA, Vol. 83, 1986, pp. 7475-7479; W T Green Jr., Clin. Orth. Rel. Res., Vol 124. 1977, pp. 237-250; C A Vacanti et al., J. Plas. Reconstr. Surg., 1991; 88:753-9; P A Lucas et al., J. Biomed. Mat. Res., Vol. 24, 1990, pp. 901-911. The ability to create human cell lines in tissue culture will enhance the prospect of cell transplantation as a therapeutic mode to restore lost tissue function. It is especially vital to be able to create human cultured cell lines from tissues of the neural crest, since tissues or organs derived from that origin couldn't usually repair itself from damage after an individual reaches adulthood.
Conventional tissue culture lab wares useful in growing cells in vitro, are usually coated with a negative charge to enhance the attachment and sometimes proliferation of mammalian cells in culture. However, traditionally it has been most difficult to achieve a satisfactory attachment, maintenance, and propagation of mammalian neuronal cells with the conventional tissue culture surfaces. Adding layers of collagen gel has made improvements or depositing an extracellular matrix secreted by rat EHS tumor cells onto the tissue culture plates and dishes to facilitate neural cell attachment and proliferation. These techniques, however, are hindered by the shortcoming that the material has to be layered on the culture surfaces shortly before the cells are seeded.
The present invention contemplates the use of 3 types of polymers to create a scaffold for cell growth and penetration: biopolymers (polymers formed in a living organism: collagen, gelatin, etc), synthetic polymers (chemically synthesized outside of the body: acrylates, polyvinyl alcohol, etc) and a combination of biosynthetic polymers. The present invention contemplates the use of these polymers as a scaffold to support the attachment, growth, and eventually as a vehicle to supporting the cells during transplantation. This use is vital to the success of cell replacement therapy, particularly in the brain and the back of the eye, where cells derived from the neural crest origin is often damaged during the aging process. There are seven general classes of biopolymers: polynucleotides, polyamides, polysaccharides, polyisoprenes, lignin, polyphosphate and polyhydroxyalkanoates. See for example, U.S. Pat. No. 6,495,152. Biopolymers range from collagen IV to polyorganosiloxane compositions in which the surface is embedded with carbon particles, or is treated with a primary amine and optional peptide, or is co-cured with a primary amine-or carboxyl-containing silane or siloxane, (U.S. Pat. No. 4,822,741), or for example, other modified collagens are known (U.S. Pat. No. 6,676,969) that comprise natural cartilage material which has been subjected to defatting and other treatment, leaving the collagen II material together with glycosaminoglycans, or alternatively fibers of purified collagen II may be mixed with glycosaminoglycans and any other required additives. Such additional additives may, for example, include chondronectin or anchorin II to assist attachment of the chrondocytes to the collagen II fibers and growth factors such as cartilage inducing factor (CIF), insulin-like growth factor (IGF) and transforming growth factor (TGFβ).